Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

Expect very dangerous avalanche conditions Thursday night into Friday as wet snow and rain fall to 5,000ft. Friday isn't a great day to go into avalanche terrain as the warmup continues.  Avalanches could run naturally from steep open slopes, so stay off of, and well out from underneath them.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    Wet loose and wet slabs should be expected as snow changes to rain on Friday. The snowpack should become wetted by rain up to around 5,000ft, so expect these to be commonplace on steep slopes and could originate from ridgetops. Slides could become large and gouge down to the crust from Christmas. Signs of wet loose avalanches are rollerballs and wet, chunky debris.

    Make sure to stay off of steep slopes, and well out from underneath them as precipitation continues.

    Large, dirty loose wet slides in the Highway Chutes across from Highway 2 on the west side of Stevens Pass during a previous season.

    Photo: Matt Primomo

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–2.5

    Around 6-8" of dense, heavy snow fell on Thursday, and should continue to slowly add up into Friday. The new snow is likely becoming quite deep at upper elevations. At lower elevations, we expect a changeover to rain on Friday. Expect 'upside down' storm snow. Slabs may just be the depth of the new snow, but there are a number of slightly deeper layers that could make for larger and more destructive avalanches if they step down. Large, upper elevation starting zones could run naturally overnight into Friday.

    Your best bet is to stay safe is to avoid avalanche terrain. Stay well away from steeper slopes, and stay off of slopes steeper than 30 degrees. Signs of instability you could come across are natural avalanches, fresh debris piles, and shooting cracks.

    Storm slabs like this may be easily triggered on Thursday

Avalanche Discussion

SPMR snow safety reported easily triggering lots of small storm slab avalanches on Thursday morning. The precipitation lightened up during the daytime, and remained as snow at pass level. Brief periods of visibility allowed an observer to report that no natural avalanches had occurred in the Highway Chutes on the N side of the pass. With snow levels expected to rise to about 5,000ft, on Friday, that could change. As the new snow slowly adds up and temperatures continue to warm, our uncertainty and confidence in the upper elevation snowpack is decreasing. All of this to say, let the storm and avalanches run their course. The snowpack will need some time to adjust to this one.

On Wednesday, I found a number of potential failure layers for this next storm while skiing on the periphery of Stevens Pass Mtn Resort. Since around January 4th, theres been about 12" of accumulated snow at mid and upper elevations. Just to the east, recent storms have amounted to higher snow totals near Leavenworth and Wenatchee. Many widely propagating ski triggered avalanches have occurred, with a layer of buried surface hoar being the culprit. This layer could be problematic in the eastern edge of the Stevens Pass zone.

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